The first thing that stands out is the website, YYY.AHB.MSK/etc. Because of the formatting, we can assume it's a simple substitution cipher, and see what happens (we're not wrong). What website might this be? WWW.FBI.GOV, perchance? I think yes. The sentence with the URL begins with KBVBF, which is probably a verb in reference to the URL. What can we do to URLs? Go to them? Not five letters. Visit them? I think yes, given: visit, kbvbf. Keep doing this for a few more minutes (or, be smart/lazy and write a quick decoder), and you'll get the finished product:

"Stupendous. We congratulate you on cracking this latest encryption. visit www.fbi.gov/coded.htm to let us know of your success." Where, presumably, they log your IP. Thanks, FBI. You make us feel important.